Defence Minister Harjit Sajjan says Canada will lead one of NATO's four new battle groups being established on the alliance's eastern flank as part of its stepped up deterrent against Russia.

Sajjan tells The Canadian Press that Prime Minister Justin Trudeau will announce the exact size of that contribution at next week's NATO leaders' summit in Warsaw, Poland.

He says the move is designed to show Canadian solidarity with NATO against Russia, which has annexed the Crimean Peninsula in Ukraine and backed pro-Russian separatist forces in that country's eastern region.

Sajjan says the hope is still to be able to re-establish a dialogue between the 28-country alliance and Russia in an attempt to dial down what is widely seen as the worst conflict between the Kremlin and the West since the end of the Cold War.

U.S. President Barack Obama urged Canada on Wednesday to make a greater contribution to NATO during his speech to Parliament in Ottawa.

Obama said NATO is more secure when every member country, including Canada, contributes its "full share" to the alliance.